modulation system

例句：

1. 1.The modulation system is used to adjust the frequency of a signal.
   调制系统用于调整信号的频率。
2. 2. The modulation system was designed to improve the quality of audio signals.
   调制系统被设计用来提高音频信号的质量。
3. 3.The modulation system is essential for transmitting high-definition video over long distances.
   调制系统对于在长距离上传输高清视频是必要的。